The proposed research is an investigation of the maturation of vestibular function in man, and the development of retinal dominance over vestibular input in respect to self-orientation in space. Almost no systematic data are available on the maturation of vestibular function or visual-vestibular interaction in the human child. In the proposed research, several parameters of vestibular nystagmus will be quantified in infants and children of different ages and in adults. These will include the slow phase amplitude and velocity, the fast phase amplitude and velocity, and latency of nystagmus in response to various magnitudes of acceleration and deceleration. The per-acceleration and post-acceleration primary nystagmus and the secondary nystagmus parameters will be treated separately and compared with each other. These parameters of vestibular function will be compared to measures of oculomotor function, which are neurophysiologically related to vestibular function. Two types of influence of peripheral retinal input over the vestibular nystagmus will be studied: circularvection effects and diffus light. Altogether, these measures will provide a systematic approach to the investigation of the maturation of vestibular adaptation and retinal-vestibular interaction in respect to the development of self-orientation in space. They will be integrated, using statistical procedures developed in systems theory, into an empirically justified block diagram, or developmental series of block diagrams illustrating the quantitative interactions between subsystems of the vestibulo-ocular system including its peripheral and central components and visual vestibular interaction.